The problem of induction is a notorious philosophical problem concerning inductive inferences; more specifically, whether that form of reasoning is generally reliable or rationally justified. An inductive inference aims to draw a general conclusion from a series of particular observations. For example, if I observe one thousand swans, and every one of those swans is white, I can infer inductively that probably all swans are white, and on that basis predict that any future swans I observe will (probably) be white. Unlike deductive inferences, in which the conclusion follows necessarily from the premises, inductive inferences cannot deliver absolute certainty—for example, the possibility of observing a non-white swan in the future cannot be decisively ruled out—but all else being equal, the greater the number of past observations confirming a general law or pattern, the stronger the inductive conclusion becomes.
Inductive inferences have been widely used in scientific research to discover laws of nature. To take one example, Newton’s universal law of gravitation was inferred inductively from empirical observations of the attractive forces between two masses. We haven’t observed the forces between every pair of masses in the universe at every point in time, of course, so we don’t have direct and infallible knowledge of a universal law. Nevertheless, we have made enough observations to be confident that they are instances of a universal law, and we can make reliable predictions about future events by positing that the universal law holds.